chore(ai-openrouter): bump @openrouter/sdk to 0.12.79

The getVideoContent response-matcher bug is still present in 0.12.79 (the
stream matcher only accepts application/octet-stream while the endpoint
serves video/mp4), so the direct unsigned-URL download stays. Link the
aimock feature request (CopilotKit/aimock#261) from the e2e matrix
exclusion. Submit/poll/download lifecycle re-verified live on the new SDK.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: tombeckenham

packages/ai-openrouter/package.json

@@ -60,7 +60,7 @@
     "model-router"
   ],
   "dependencies": {
-    "@openrouter/sdk": "0.12.35",
+    "@openrouter/sdk": "0.12.79",
     "@tanstack/ai-utils": "workspace:*"
   },
   "devDependencies": {